Superconductive copper-oxide perovskite materials have excited great interest because certain of these materials have transition temperatures to the superconductive state which are a higher than previously-known superconductive materials. Although such superconductive materials have transition temperatures and critical current densities which are high enough for many applications, the ability to alter and improve such parameters would be desirable.
It is known that applying a uniform hydrostatic pressure to certain yttrium barium copper oxide superconductive materials can cause the superconductive transition temperature T.sub.c to increase.
A publication by Triscane et al., in Physical Review Letters, volume 63, pages 1016 through 1019 (28 August 1989) discloses certain epitaxially grown materials of YBa.sub.2 Cu.sub.3 O.sub.7 and DyBa.sub.2 Cu.sub.3 O.sub.7 described as "superlattice" materials in which planes of dysprosium replace planes of yttrium down to a superlattice "wavelength" of twice the c-axis lattice parameter. It is indicated in the publication that modulation of the rare-earth planes takes place within a Ba--Cu--O matrix and that the 1:2:3 structure "does not care" whether dysprosium or yttrium occupies the rare-earth sites. According to the article, the superconducting properties of the superlattices are as good as single layers, with transition temperatures T.sub.c0 between 85.degree. and 88.degree. K.